Lighting unit



Nov. 4, 1941.

w. NERL'ICH ETAL LIGHTING UNIT Filed May-23, 1939 2 Sheets-Sheet l-Willi $5 WITNESSES:

INVENTORS. Nerlzch s Sezdel A noa EY w. NERLICH ETAL' LEIGHTING UNIT r%/Fi led May 23, 1939 2 She ets-Sheet 2' INVENTORS Willi Nerlich 8: Hot 8Nov. 4, 1941.

WITNESSES:

Patented Nov. 4, 1941 UNITED STATES PATENT. OFFICE LIGHTING UNIT WilliNerlich, Berlin-Spanda'u, and Hans Seidel,

Berlin-Falkensee, Germany, assignors to Westinghouse Electric &Manufacturing Company, a corporation of Pennsyl East Pittsburgh, Pa,

vania Application May 23, 1939, Serial No. 275,194 In Germany July 26,1938 7 8 Claims.

Our invention relates, generally, tolighting units, and, moreparticularly, to lighting units of the explosion-proof type.

The object of our invention, generally stated, is to provide a lightingunit which shall be of simple and rugged construction, which may bereadily and economically manufactured and maintained, and which willprovide a high degree of safety in its operation and use.

A more specific object of our invention is to provide a lighting unit ofthe enclosed or explosion-proof type which cannot be opened to gainaccess to the lamp therein until the lamp,

switch contained therein has been actuated to its open position tointerrupt the lamp circuit.

Another object of our invention is to provide a lighting unit having thelamp controlling switch mounted within the unit and switch actuatingmeans on the outside of the unit so arranged that the unit cannot bedisassembled while the switch is in its closed position.

A further object of our invention is to provide an explosion-prooflighting unit having a safety chamber containing the terminals and apressure chamber containing the lamp socket with electrical connectionsextending between said chambers through explosion-proof seals ofpredetermined length.

A still further object of our invention is to provide for forming anexplosion-proof lighting unit 1 by an assembly comprising a cap member,a housing member detachably secured thereto to form a safety chamber forhousing the terminal members and a globe attached to the housing memberto form a pressure chamber for housing the lamp socket, lamp andlamp-controlling switch.

Another object of our invention is to provide, in an explosion-prooflighting unit of the character described, for mechanically interlockingthe various parts comprising the cap member, housing meter and globe,together in such manner that they cannot be disassembled until the lamp.controlling switch mounted within the unit has been opened.

These and other objects of the invention will become more apparent fromthe following detailed description when read in conjunction with thedrawings in which:

Figure 1 is a sectional view partly in elevation of a lighting unitembodying the principal features of our invention;

Fig. 2 is a view of one of the elements of the unit of Fig. 1;

Fig, 3 is a partially sectionalized top plan view safety chamber Ill.

of the unit of Fig. 1 showing the lamp controlling switch within theunit;

Fig. 4 is an elevational view of the unit of Fig. 1 showing thearrangement and the relative position of the switch actuating device andthe locking device for the globe ring;

Fig. 5 is a View in section of the unit taken along lines V-V of Fig. 3;and

Fig. 6 is a detail view taken along line VIVI of Fig. 4 showing detailsof the locking device for the globe ring.

In the preferred embodiment of the invention, the lighting unit isprovided with a built-in switch and is constructed in such manner thatit can only be opened after the circuit of its incandescent lamp hasbeen interrupted, while on the other hand, the latter circuit cannot beclosed unless all parts of the unit have been properly put together andbrought into the closed positions. The lighting unit in line with theinvention has a. closed safety chamber containing the terminals to whichthe lead-in wires must be fastened, and a sealed pressure chambercontaining the incandescent lamp, lamp socket and the switch. Betweenthese two chambers there have been provided conductive connections inthe form of contact-making pins or plugs which lead from the safetychamber that contains the terminals, through explosion-proof seals.

of predetermined length, into the pressure chamber, where they areinserted in contact-making sleeves.

Referring now to the drawings, the lighting unitcomprises a cap I, ahousing 2, a glass casing or globe 3, and a supporting ring 4 withbayonetcatch for the dome-shaped wire-guard 5. Inside the cap I of thelighting unit is mounted a terminal cleat 6, of insulating material,which carries the terminals I. The housing 2-of the lighting unit isheld against the cap I and is fastened to the latter by means of screws8. At the joint of the two parts I and 2 there has been provided .agasket '9 of rubber or other suitable material, so that these two partsform a sealed The glass casing or globe 3 bears against the bottom partof the housing 2 of the lighting unit to form a pressure chamber lila.This glass casingv or globe 3' is pressed against the bottom part of thehousing 2 by the ring 4 with bayonet-catch, a rubber gasket H beinginserted between the surfaces of 3 and 4 that are being pressedtogether, and a ring [2 of aluminum foil being inserted between thesurfaces of 2 and 3 that are being pressed together.

The arrangement of the bayonet-catch is indicated in Fig. 1. Thesupporting ring 4 has a bayonet-catch in the form of a nose l3 whichslides into position behind a corresponding nose M of the housing 2 ofthe lighting unit.

Inside the housing 2 is mounted a socket |5 for the incandescent lampIS; The housing contains in addition a switch I! which is actuated by ashaft |8 equipped with a coupling-pin IS. The shaft 8 is led through ahole of the housing 2 of the lighting unit, in such a manner that anexplosion-proof seal of predetermined length, such for example, as aboutseven-tenths of an inch, is formed.

The switch is actuated with the aid of a key 20 which has two jaws 2|and 22 that engage the coupling-pin l9. The key 2|] is supported by ahinged part 23 that can be swung around a fulcrum 24. The chamber 25which accommodates said key is partly closed by means of a disc 26 ofsheet metal as shown in Fig. 2. This disc can be equipped, for instancewith two'slits21, so that the key 20 can only be inserted into thechamber 25 when it is being held in a quite definite position, i. e., inthe position corresponding to the off position of the switch.

A rotational displacement of the supporting ring 4 with bayonet-catchwith-respect to the housing 2 of the lighting unit is made impossible bya threaded bolt 28, as shown in Fig. 6, which is attached to a lug 29 ofthe supporting ring 4. This threaded bolt passes through the hole of alug 30 and is held in position by a nut 3|. This nut may be equipped,for instance, with a triangular head 32. As soon as one loosens this nut3|, it is pushed outward in the direction of the arrow by the force of aspring 33 until it protrudes beyond the part 30. The hinged part 23 hasbeen so designed that upon the insertion of the key 20 into thekey-chamber 25, part 23 will be standing directly in front of thetriangular head 32 of the nut 3|. In other words, the nut cannot beloosened after the insertion of the key 20 into the key-chamber, and itis impossible, therefore, to open the pressure-chamber of the lightingunit in this case. The triangular head 32 of the nut 3| will only beaccessible after the key 20, upon being brought into the off position,is removed by swinging the hinged part 23 downward. On the other hand,the nut 3| will remain in the position in which it partly protrudesbeyond the part 30 as long as it is not screwed again on the threadedbolt 28, and as long as the nut remains in this position, the hingedpart 23 cannot be swung upward again for the purpose of inserting thekey of the switch into the key-chamber.

In order to make it impossible to separate the cap I from the housing 2of the lighting unit under operating conditions, the supporting part orring 4 has been equipped with lugs 34 which, when this part is in theclosed position, are placed directly in front of the heads 35 0f thescrews 8, so that the latter are not accessible in this case. This meansthat the chamber ||l cannot be opened until after the switch has beenbrought into the off position, the connection established by thethreaded bolt 28 and the nut 3| has been loosened, and the supportingring 4 with the bayonet-catch has been turned through a certain angle.

Current is transmitted from the safety chamber ID to the pressurechamber 0a of the lighting unit by means of contact-making pins or plugs36 which are led through a part 31 of insulating material in'such amanner that explosion-proof seals are formed. It is preferable to makethese seals about seven-tenths of an inch in length. Inside the pressurechamber, these pins or plugs are inserted in contact-making sleeves 38which may be connected to the switch I! and socket IS in any suitablemanner to complete the electrical connection to the lamp 6.

In view of the foregoing it will be apparent that we have provided alighting unit of the explosionproof type, wherein the various parts ofthe unit are assembled in such manner that they cannot be disassembledor the unit opened while the lamp controlling switch, positioned withinthe unit, is in the closed position and the switch cannot be actuated toits closed position to supply current to the lamp until the variousparts of the units have been properly assembled. The unit is alsoprovided with separate chambers, one of 'which houses the terminalmembers and the other houses the lamp, its socket and controllingswitch, and sealed explosion-proof connectors provided between the twochambers. Likewise, the switch is actuated by means of a shaft extendingthrough a sealed explosion-proof opening in the side of the housing,thereby providing a completely enclosed unit of the explosion-proof typewhich is of simple and inexpensive construction and which provides amaximum degree of safety.

It may be stated, in conclusion, that while the illustrated exampleconstitutes a practical embodiment of our invention, we do not wish tolimit ourselves strictly to the exact details herein illustrated, sincemodifications of the same may be made without departing from the spiritof the invention, as defined in the appended claims.

We claim as our invention:

1. A lighting unit comprising, a housing member, a globe, a supportingring for the globe, said ring being attached to the housing by a bayonetjoint, said globe and housing forming a chamber, a lamp socket mountedwithin said chamber, a lamp controlling switch mounted within thechamber, a shaft extending through the housing for actuating the switchfrom outside the housing, key means mounted on the outside of thehousing and movable into and out of engagement with the exposed end ofthe shaft for actuating the shaft, and locking means mounted on theoutside of the housing for holding the globe ring in locked position,said key means and locking means being so disposed that the key meanscannot be moved into engagement with the end of the shaft to actuate theshaft unless the locking means is in its locking position, thereby toen-' sure that the globe is securely attached to the housing before thelamp controlling switch may be operated.

2. A lighting unit comprising, an inverted cup-shaped cap member, ahousing disposed to be attached to the bottom of the cap member to forma, first chamber, a plurality of screws extending through the rim of thehousing into the cap member to detachably secure the housing thereto, aglobe disposed to be attached to the bottom of the housing to form asecond chamber, a globe ring attached to the housing to hold the globein position, and lug portions on said globe ring disposed to cover theexposed heads of said screws to render them inaccessible when said globering is in a predetermined position, thereby to prevent the opening ofthe safety chamber while the pressure chamber is closed.

3. A lighting unit comprising, a metal top portion, a globe detachablysecured to the bottom thereof forming a closed pressure chamber, meansfor locking the globe in closed position, a lamp socket mounted in saidchamber, a switch also mounted in said chamber, a shaft extendingthrough the top portion for actuating the switch, a key for actuatingsaid shaft, a lever pivotally mounted on the outside of the housing forsupporting said key, whereby said key may be swung out of and intoengagement with the shaft, said lever and locking means being mounted inmechanical interlocking relation to preclude operation of the lockingmeans when the key is engaging the shaft and means positioned over theend of the shaft whereby said key and shaft may be engaged anddisengaged only when the switch is in the ofi position.

4. A lighting unit comprising, a metal top portion, a globe disposed tobe attached to the bottom of said top portion to form a pressurechamber, a globe ring for attaching the globe to the top portion, meansfor detachably securing the globe ring to the bottom of the top portion,means for locking the globe ring to the top portion after it has beensecured thereto, a lamp socket and switch mounted in the pressurechamber, a shaft extending through the said top portion for actuatingthe switch, a key for actuating the shaft, a lever hinged to the outsideof the top portion for movably supporting the key whereby said key maybe moved into and out of engagement with the end of the shaft, saidhinged lever being so disposed for movement with respect to the lookingmeans for the globe ring that said locking means is renderedinaccessible by the hinged lever for operation to unlock the ring whilesaid key is engaging the end of the switch actuating shaft.

5. A lighting unit comprising, a cap member, a housing member attachedthereto to form a safety chamber, a globe disposed to be attached to thebottom of the housing member to form a pressure chamber, a globe ringfor attaching the globe to the housing, said globe ring being attachedto the housing by a bayonet connectionwhich functions to secure saidglobe ring to the housing on predetermined rotational movement of theglobe ring relative to the housing, retaining means attached to theglobe ring and engaging the housing to lock said globe ring in position,a lamp socket and switch mounted in the pressure chamber, a switchactuating member extending through the side of the housing, a key foractuating the shaft, a lever hinged to the outside of the housing forsupporting the key, said lever and said retaining means being sodisposed with respect to one another that said lever cannot be movedinto position to cause the key to engage the shaft until said retainingmeans has been operated to lock the globe ring and said retaining meanscannot be operated to unlock the globe ring while said lever is inposition to cause the key to engage the shaft.

6. A lighting unit of the explosion-proof type comprising, a cup-shapedcap member, a housing attached to the bottom of the cap member to form aclosed safety chamber, said housing having a pair of openings in thebottom thereof, a pair of terminal members supported by the cap memberwithin the safety chamber, a globe detachably secured to the housing toform a pressure chamber, a lamp socket mounted in the pressure chamber,a switch mounted in the pressure chamber, a pair of contact membersmounted on the underside of the housing within the pressure chamberdirectly beneath said openings, said contact members being connected tothe switch and lamp socket, a pair of rigid contact pins stationarilymounted in the safety chamber and supported from the cap member andextending through the openings in the bottom of the housing intoengagement with the contact members in the pressure chamber, saidcontact pins being connected with the terminal members in the safetychamber, means interposed between the contact pins and sides of theopenings for sealing the joints therebetween, and a shaft extendingthrough a sealed opening in the side of the housing for operating thesafety switch.

7. A lighting unit of the explosion-proof type comprising, an invertedcup-shaped cap member having a plurality of threaded openings disposedaround the periphery thereof, a housing member disposed to be attachedto the bottom of the cap member to form a safety chamber for housing aplurality of wiring terminals, said housing having a plurality ofoutwardly extending ear portions provided with openings, a headed screwdisposed in each of said openings in the ear portions and engaging thethreaded openings in the cap member for clamping the housing against thebottom of the cap member, a globe, and a globe ring for attaching theglobe to the bottom of the housing to form a pressure chamber forenclosing the lamp and lamp socket, said globe ring being attached tothe housing by a bayonet joint and having outwardly extending lugscovering the heads of said screws when in its attached position topreclude opening of the safety chamber while the globe is in position.

8. A lighting unit of the explosion-proof type comprising, an invertedcup-shaped cap member, a housing member detachably secured to the bottomthereof with a sealed joint therebetween to provide a safety chamber,said housing having a plurality of openings therein, a globe, means forsecuring the globe to the housing with the joint between the globe andhousing sealed to form a pressure chamber, a lamp socket and a controlswitch mounted within the pressure chamber, a shaft extending through anexplosion-proof sealed opening in the side of the housing for actuatingthe switch, a plurality of terminal members fixedly mounted within thesafety chamber, a plurality of contact members fixedly mounted withinthe pressure chamber and electrically connected with said lamp socketand control switch, and a plurality of rigid contact pins fixedlymounted within the safety chamber and electrically connected to theterminal members therein and extending through the openings in thehousing into engagement with the contact members therein, said openingsbeing provided with explosion-proof seals around the contact pins andsaid contact pins being disposed in sliding relation therewith.

WILLI NERLICI-li. HANS SEIDEL.

